1. Technical Field
The present invention relates generally to liquid heaters, and more specifically, to a positive temperature coefficient heater.
2. Background
Currently, positive temperature coefficient (“PTC”) heaters are widely applied in household appliances such as spa pools, entertainment pools, water dispensers, foot baths, and other industrial products.
A PTC heater, which is commonly known in the art, includes a heat conductor, PTC heating elements, and end covers having a water inlet and a water outlet. The heat conductor includes a plurality of ducts separated from one another, where some of the ducts are used for housing PTC heating elements, and some of the ducts are used as liquid passage channels. The end covers are coupled to each axial end of the heat conductor, first serving as liquid passage channels in fluid communication with the heat conductor, and secondly serving to seal each end of the duct in which a PTC heating element is placed within the heat conductor.
A disadvantage of these types of PTC heaters lie in the fact that the entire PTC heating element, aside from wires is disposed in the duct of the heat conductor. Also, end faces of the end covers butt directly against end faces of the heat conductor, and the PTC heating element is positioned inside of the end covers. Once the end covers are sealed with the heat conductor, water permeates or leaks through the joining faces of the end covers and the heat conductor and drip on or otherwise come into contact with the PTC heating element.
Additionally, the housing of existing PTC heating elements is a tubular metal piece. A heating assembly, electrode sheets, and insulating paper are disposed within the housing, and each end of the tubular housing is sealed with rubber plugs or an insulation paste. Once the rubber plugs and the insulation paste are damaged, a gap or space is created at the ends of the tubular housing that permits water to seep into the interior of the housing. This may cause electricity to leak from the heater, resulting in an electrical short or damage to electrical components coupled to the heater.
Thus, a need therefore exists for heating unit that overcomes the disadvantages and safety risks found in currently known PTC heaters. In particular, there is a need for a PTC liquid heater that improves safety, is simple in structure, and effectively prevents electricity from leaking out of the heater.